System and method of authenticating an article

ABSTRACT

A method of authenticating an article includes the steps of, at an issuing station, selecting an inherent feature of the article and converting the feature into digital data to form an identification code for the article. An encryptor is used to encrypt the identification code utilizing a secret private key of an asymmetric encryption key pair and associated with the issuing party. The encrypted code is made available on a label accompanying the article. During a subsequent phase and at an authentication station, digital data relating to the feature is determined directly from the article and the code is decrypted utilizing a public key of the pair obtained from a third party in accordance with rules of a public key infrastructure. The determined data and the data relating to the feature retrieved from the decrypted code are compared to authenticate the article.

This application is the US national phase of international applicationPCT/ZA02/00070, filed in English on 02 May 2002, which designated theUS. PCT/ZA02/00070 claims priority to ZA Application No. 2001/7316 filed04 Sep. 2001. The entire contents of these applications are incorporatedherein by reference.

TECHNICAL FIELD

THIS invention relates to a method and apparatus for certifying andauthenticating a product or article.

A method of tracking an article wherein a secure code is applied to thearticle is disclosed in South African patent 97/6663. A problem withthis method and system is that the proposed codes are cloneable whichwould compromise the method and system.

OBJECT OF THE INVENTION

Accordingly it is an object of the present invention to provide a methodand system with which the applicant believes the aforementioned problemsmay at least be alleviated.

SUMMARY OF THE INVENTION

According to the invention there is provided a method of certifying anarticle, the method comprising the steps of:

-   -   selecting an inherent feature of the article which is unique to        one of:        -   the article; and        -   a group of such articles to which the article belongs and            digitizable in the form of digital data uniquely defining            the article or group;    -   forming an identification code comprising the digital data; and    -   making the identification code available.

The term “article” is used in this specification to denote naturallyoccurring or produced objects as well as artefacts, including digitalproducts.

The identification code may be encrypted by utilizing one key of a pairof asymmetric encryption keys comprising a private key and a public keyassociated with a party performing or issuing the certification. Theencryption is preferably performed utilizing the private key.

The private key is preferably a secret key and the public key may becontrolled by a trusted third party according to rules of a public keyinfrastructure (PKI).

The code may be made available to the public by applying it to thearticle. The code is preferably applied to the article in a human and/ormachine readable form, for example in the form of a bar code applied tothe article, alternatively on a separate certificate, furtheralternatively on a label accompanying the article and still furtheralternatively and in a suitable application, included in a digitalcarrier, such as a digital watermark.

The inherent feature of the article may be the result of manipulation ofthe article, for example chemical manipulation or marking of thearticle, to embed a unique feature in or on the article.

The identification code may also comprise further data, such as datatrue to the article, for example historic data relating to the article.Such data may comprise data relating to an origin and/or an issuer ofthe article.

According to another aspect of the invention, a method of authenticatinga certified article comprises the steps of:

-   -   receiving the article together with an identification code        comprising digital data relating to an inherent feature which is        unique to one of the article and a group of such articles to        which the article belongs;    -   from the article, determining data relating to the inherent        feature; and    -   comparing said digital data in the identification code to the        determined data relating to the inherent feature.

The identification code may be received in a form wherein it isencrypted by a private key of an asymmetric key pair also comprising apublic key and the public key may be retrieved from a trusted thirdparty and utilized to decrypt the identification code, before comparingsaid digital data in the identification code to the determined datarelating to the inherent feature.

Also included within the scope of the present invention is a method ofauthenticating an article comprising the steps of:

-   -   at an issuing station:        -   selecting an inherent feature of the article which is unique            to one of the article and a group of such articles to which            the article belongs and which is digitizable in the form of            digital data;        -   forming an identification code comprising the digital data;        -   encrypting the identification code with a private key of an            asymmetric encryption key pair also comprising an associated            public key, to form an encrypted identification code; and    -   at an authentication station        -   from the article, determining data relating to the inherent            feature;        -   utilizing the public key to decrypt the encrypted            identification code, to yield decrypted data; and        -   comparing said determined data and said decrypted data.

Further included within the scope of the present invention is a systemfor certifying an article, the system comprising:

-   -   apparatus for analyzing the article and converting an inherent        feature of the article which is unique to one of the article and        a group of such articles to which the article belongs into        digital data; and    -   a data processor for forming an identification code for the        article comprising said digital data.

The data processor may comprise an encryptor for encrypting theidentification code utilizing a private key of an asymmetric encryptionkey pair also comprising an associated public key.

Still further included within the scope of the present invention is asystem for authenticating a certified article, the system comprising:

-   -   apparatus for analyzing the article and for deriving from the        article digital data relating to an inherent feature which is        unique to one of the article and a group of such articles to        which the article belongs; and    -   a data processor for comparing the derived data and an        identification code supplied with the article and which code        comprises digital data relating to the inherent feature.

The identification code may be supplied in a form wherein it isencrypted by a private key of an asymmetric encryption key pair alsocomprising a public key and the data processor may utilize said publickey to decrypt the encrypted identification code, before comparing thederived data and the identification code.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only,with reference to the accompanying diagrams wherein:

FIG. 1 is a block diagram of a certification system according to theinvention;

FIG. 2 is a flow diagram of a certification stage of an authenticationmethod according to the invention;

FIG. 3 is a diagrammatic illustration of a subsequent authenticationstage of the method according to the invention;

FIG. 4 is a block diagram of a second embodiment of the system forcertifying compact discs;

FIG. 5 is a block diagram of a third embodiment of the system forcertifying automobile tyres;

FIG. 6 is a block diagram of a fourth embodiment of the system forcertifying pouches of uncut or raw diamonds;

FIG. 7 is a diagram of a negotiable instrument that may be authenticatedin accordance with the method of the invention;

FIG. 8 is a block diagram of a fifth embodiment of the system forauthenticating so-called intelligent smart cards; and

FIG. 9 is a flow diagram illustrating a sixth embodiment of the systemfor certifying a digital artefact.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

A system and method for certifying and authenticating an article such asa diamond 10 is illustrated in FIGS. 1 to 3.

The system 12 comprises an analyzing device, for example an opticalscanner 14 and digitizer 16 for converting a selected inherent uniquefeature of the diamond into a string of digital data 18. The uniquefeature may relate to one or more of flaws in the diamond, size of thediamond, color of the diamond, etc. The digital data hence defines thediamond 10 uniquely enough in terms of inherent features of the diamond.Since no two diamonds are identical in the aforementioned respects, astring of digital data 18 defining a first diamond differs from asimilar string of digital data defining a second diamond.

At adder 20, other truth data 21 about the diamond may be added to thestring of digital data 18 to form an identification (ID) code 22 for thediamond. This truth data may comprise data relating to the name of anissuing institution such as a mining company (MCO) that mined thediamond, data relating to a date (xx/yy/zz) on which the diamond wasmined and data (ABC) relating to the location (e.g. country anddistrict) of the mine where the diamond was mined. It will beappreciated that the other truth data is not necessarily unique to aparticular diamond.

At encryptor 24 the ID code 22 is encrypted in known manner utilizing aprivate key 26 of a pair of asymmetric keys, to form an encrypted IDcode 28. The encryption is performed in accordance with known rules andconventions of a public key infrastructure (PKI) comprising a trustedthird party as certification authority (CA). It is well known that insuch an infrastructure the key pair comprising the private and a publickey is generated. The private key is kept secret by the intended user(in this case the issuing institution, such as the mining company) andthe public key is controlled and made available to prospective users bythe CA through the infrastructure. It is further known that only thepublic key can decrypt what was encrypted-utilizing the private key andvice versa.

The encrypted ID code 28 is made available to the public at 30 on aseparate printed certificate (not shown) or in any other suitablemanner. In a preferred form, the encrypted code 28 is applied to thearticle 10, for example in the form of a bar code 32 on a label 31accompanying the diamond.

The steps in the certification or issuing stage of the method accordingto the invention referred to herein before are illustrated in FIG. 2. At40, the unique feature is identified and the feature is digitized at 42to yield digital data 18. The other truth data is added at 44 and at 46the encrypted ID code 28 is formed by encrypting the plain text ID code22 utilizing the private key 26 of the mining company. The encrypted IDcode is applied to the diamond 10 in the form of a bar code on the label31 accompanying the diamond, as illustrated at 48 in FIG. 2.

Referring to FIG. 3, authenticity of a diamond issued as hereinbeforedescribed, is determined by an article authenticator utilizing thefollowing steps. The article authenticator may be a jeweler and thediamond may be offered to the jeweler by a party claiming the diamond tohave the properties set out in known manner in the aforementionedaccompanying certificate, including the name of a claimed issuinginstitution.

In a first step 50 which is similar to step 42 in FIG. 2, the jewelerdetermines directly from the diamond digital data 18′ relating to theunique features of the diamond. By utilizing the name of the claimedissuing institution, the jeweler retrieves via the PKI in well knownmanner the public key 51 of the claimed issuing institution as shown at52.

At 54, the encrypted ID code 28 is read by reading bar code 32 in knownmanner. At 56 and by utilizing the public key 51, the encrypted ID code28 is decrypted to obtain digital data 18. In a case where no identityof an issuing institution is claimed, the jeweler may determine theissuing institution by sequentially trying, through a process ofelimination, the retrieved public keys of well known issuinginstitutions in the relevant industry, until the encrypted ID code 28 issuccessfully decrypted.

At 58, data 18′ and data 18 are compared and if the portions thereofrepresenting the unique features of the diamond are the same, thediamond is determined to be what the claimant claims it to be, as shownat 60. If not, and as shown at 62, the claims about the identity and theorigin of the diamond are proved to be questionable.

In another application, discs, such as compact discs (CD), carryingdigital data, including recorded music or computer software, may becertified and authenticated.

A manufacturer 70 of blank discs may manufacture the plastic disc bodywith higher density plastic particles embedded therein to provide apattern 72 of such particles embedded in the disc body 74. However,depending on factors such as the resolution of pattern scanningapparatus, the patterns may randomly fall into n groups or classesnamely, class #1 to class #n of discs, wherein each class accommodatesdiscs having substantially the same pattern so embedded. The number ofclasses and size of a class would be determined by the resolution of theequipment. Hence, the value of n may be determined and then the scanningand/or implanting equipment is selected such as to make cloning of thesystem not economically viable for a pirate or copying party.

At a content provider 76, the blank CD body 74 of which theaforementioned pattern falls into any one of the aforementioned classes,preferably according to a flat random distribution, is scanned by ascanner 78, to provide digital data 80 relating to the pattern. Thecontent data 82, is written onto the body at 84 in known manner. Thepattern data 80 and content data 82 are encrypted at encryptor 86 ashereinbefore described by computing a hash (#) and digitally signing thesaid data and further data relating to the provider 76 with a privatekey of the content provider, to provide an encrypted identification code88. The encrypted code 88 is also written onto the CD at 90 for examplein the form of or as part of a digital watermark serving as carriertherefor.

In other embodiments, a manufacturer may cause or embed as hereindescribed in each article of a group or batch of articles a singleunique digitizable feature which is common to all articles in the group.Digital data relating to that feature may also be used in anidentification code as herein described. A typical application may be intablets or capsules, for medical use.

In the event of a suspected pirate or copied version of the CD, a lawenforcement agency for example, may scan the disc to determine thepattern data directly from the disc. The content data is also relativelyeasily establishable. A public key of the provider 76 is obtainedaccording to the PKI rules from a trusted third party and utilized todecrypt the encrypted code written on the CD as hereinbefore described,to provide decrypted data. The decrypted data and scanned pattern dataare compared to determine whether the CD originates from the genuinecontent provider 76.

In yet another application, tyres 100 shown in FIG. 5 for vehicles maybe authenticated. It is known that a tyre 100 comprises a casing 102which is normally handmade of Kevlar fiber 104 for reinforcing a rubberbody 106 of the tyre. The Kevlar casing has a random pattern with auniqueness of in the order of 1:100000. It is believed that this is acurrently economically viable uniqueness for this application. Digitaldata relating to the Kevlar pattern within a frame 108 on the tyre isobtained with a suitable scanner. Other data 110 relating to the tyreincluding data relating to the manufacturer and the pattern data areencrypted at encryptor 112, to provide an encrypted code 114. Theencrypted code 114 is applied to the tyre at 116 and/or is provided on aseparate certificate. To determine the authenticity of a tyre, thepattern in the same frame 108 must be determined. Pattern data sodetermined is then compared with the pattern data extracted from theencrypted code in a decryption process utilizing the public key of themanufacturer. If there is a match, the tyre is what it is claimed to be.

Another application is illustrated in FIG. 6. Articles such as rawdiamonds 120 may be vacuum-packed in a transparent air impermeable pouch122 having a seal 124. The shape and/or configuration of the bag may bedigitized to obtain digital data 126 relating to the shape andconfiguration which would be unique enough to a particular package 128.As in previous examples, the data 126 and other data 128 includingidentification data relating to a packager or miner of the diamonds areencrypted at encryptor 130 as hereinbefore described by means of aprivate key 132, to yield an encrypted code 134. The encrypted code maybe applied to the package 128. Subsequent authentication will be done ina manner similar to that hereinbefore described with reference to theprevious examples.

A unique enough digitizable feature may be caused or implanted in anarticle upon manufacture such as in the aforegoing example of CD bodies.Other such examples are luxury stationary, such as pens, wherein higherdensity particles or foreign particles may be added to the material fromwhich a body of the article is formed, thereby to embed a unique patternof such particles in the body. In yet other cases, the feature may becaused post manufacture. For example, small cracks may be caused inbodies of cast metals, such as aluminium, and which cracks form a randomdigitizable pattern unique, difficult and/or uneconomic enough to clone.

Similar to the example of the Kevlar pattern in the tyres described withreference to FIG. 5, grain or other patterns in a frame of a sheet orpiece of paper used for financial instruments such as bank notes,cheques and other potentially valuable paper instruments, such asscratch cards and lottery tickets may be used to authenticate suchitems.

Another example where an inherent feature of an article may be used isthe random pattern of electron sensitive regions on a cathode ray tube(CRT) used for computer and other screens and monitors.

Whereas the aforementioned examples mainly relate to digitizable imagesof at least part of an article or item, information content may also beutilized as a unique enough digitizable feature of an article. Forexample, in the case of a cheque 140 shown in FIG. 7, drawn by a bank,government institution or other body, any combination of information onthe cheque, such as data relating to the drawer bank 142, the date 144,the amount 146, the drawer 148, account number 150 and branch codenumber 152 may be encrypted utilizing a private key of the drawer 148,to yield an encrypted code. The encrypted code may be applied in humanor machine perceivable form at 154 on the cheque. Subsequentauthentication of the cheque 140 is performed in a manner similar tothat described in respect of the other applications hereinbeforedescribed.

In another application shown in FIG. 8, a so-called intelligent smartcard 160 is depicted. The card 160 comprises a plastic body 162 hostingan embedded processor 164 and associated circuitry 166 including acontact arrangement for connecting the card to external circuitry, suchas reader 168. Also carried by the body 162 is an RF transponder 170comprising a chip 172 and an antenna 174.

An encrypted code 178 encrypted by a private key of an institution 179which issued the smart card 160 is stored in a memory arrangement of thesmart card. The encrypted code 178 comprises an identification (ID) codeassociated with the smart card and one or both of an indestructibleidentification (ID) code once written only into the transponder chip 172upon manufacture thereof on the one hand and data relating to a pattern180 of high-density particles 181 or a grain within a particular frame182 on the plastic body on the other hand.

An authentication system in card reader 168 comprises a pattern scanner184 connected to a central processor 186. Contacts 188 to be broughtinto engagement with the contact arrangement on the card are alsoconnected to the processor. A reader 190 for the transponder 170 is alsoconnected to the processor 186.

When the card 160 is inserted into the card reader 168, the processor186 utilizes a public key of the issuing institution 179 to decrypt theencrypted code 178 read via contacts 188, to extract plain text datarelating to the ID code of the card, the ID code of the transponder chipand/or the pattern 180. The processor also receives data relating to thescanned pattern from scanner 184, data relating to the ID code of thesmart card received via contacts 188 and data relating to the ID code ofthe transponder received from reader 190. This data is compared ashereinbefore described to determine whether the card is a genuine cardor a fake card.

In yet another embodiment illustrated in FIG. 9, a digital artefact suchas a piece of digitally recorded music or a computer program may becertified and authenticated. In a first step 200, a digital image of atleast part of the artefact is obtained. At 202, the resolution isdetermined to ensure that the images fall according to a randomdistribution into n available classes. The classes being large enough toaccommodate image manipulation, for example by cropping and resolutionchanges, but small enough to statistically provide a unique enough classto deter fraudulent activities on an economical basis. At 204, the imagedata and other truth data relating to the artefact are combined to forma code. At 206, the combined code data is encrypted utilizing a privatekey of an asymmetric encryption key pair as hereinbefore described.Finally at 208 the encrypted code is included in a digital watermarkembedded in the digital artefact. The extraction of the relevant dataduring a second stage of an authentication process is similar to thatdescribed hereinbefore.

1. A method of certifying a plurality of articles, the method comprisingthe steps of: selecting a common inherent feature of the articles, thefeature being digitizable in the form of digital feature data; thefeature being selected, such that the articles are divided into nclasses, wherein n is smaller than the number of articles constitutingthe plurality of articles, and wherein all the articles in each classare represented by respective unique digital class feature data derivedfrom the feature; forming an identification code for each article ineach class comprising the respective unique digital class feature dataand at least one of data relating to an identity of a party performingthe method and data relating to an origin of the article; encrypting theidentification code utilizing a private key of an asymmetric key pairassociated with the party performing the method, the key pair alsocomprising a public key; the private key being a secret key and thepublic key being controlled by a trusted third party; and making theencrypted identification code available for subsequent authentication ofthe article.
 2. The method as claimed in claim 1 wherein the encryptedidentification code also comprises further data relating to the article.3. The method as claimed in claim 1 wherein the encrypted identificationcode is made available to the public by at least one of: applying thecode to the article, applying the code to a separate certificate;applying the code to a label accompanying the article; and including thecode in a digital carrier.
 4. The method as claimed in claim 1 whereinthe inherent feature of the article is the result of manipulation of thearticle.
 5. A system for certifying a plurality of articles, the systemcomprising: apparatus for analyzing a common inherent feature of thearticles and converting the feature into digital feature data, thefeature being selected such that the articles are divided into n classeswherein n is smaller than the number of articles constituting theplurality of articles, and wherein all the articles in each class arerepresented by respective unique digital class feature data derived fromthe feature; means for forming an identification code comprising therespective unique digital class feature data and at least one of datarelating to a party certifying the article and data relating to anorigin of the article; an encryptor for encrypting the identificationcode utilizing a private key of an asymmetric key pair associated withthe party certifying the article, the key pair also comprising a publickey which is controlled by a trusted third party; and means for makingthe encrypted identification code available for subsequentauthentication of the article.
 6. A method of certifying andauthenticating an article of a plurality of articles comprising thesteps of: at an issuing station, selecting a common inherent feature ofthe articles and which feature is digitizable in the form of digitalfeature data; the feature being selected such that the articles aredivided into n classes wherein n is smaller than the number of articlesand wherein all the articles in each class are represented by respectiveunique digital class feature data derived from the feature; forming anidentification code for each article in each class comprising therespective unique digital class feature data and at least one of datarelating to an identity of a party performing the method and datarelating to an origin of the article; encrypting the identification codeutilizing a private key of an asymmetric key pair associated with theparty performing the method, the key pair also comprising a public key;the private key being a secret key and the public key being controlledby a trusted third party; making the encrypted identification codeavailable at an authentication station; from the article, determiningdata relating to the inherent feature; utilizing the public key todecrypt the encrypted identification code, to yield decrypted data; andcomparing said determined data and said decrypted data.
 7. A method ofauthenticating a certified article comprising the steps of: receivingthe article together with an identification code comprising digital datarelating to an inherent feature which is unique to a group of articlesto which the article belongs, the code being asymmetrically encrypted bya first key of an asymmetric key pair also comprising another key;utilizing the other key to decrypt the code and extracting the digitaldata; from the article, determining data relating to the inherentfeature; and comparing, off-line, said digital data in theidentification code to the determined data relating to the inherentfeature.
 8. A system for authenticating a certified article, the systemcomprising: apparatus for analyzing the article and for deriving fromthe article digital data relating to an inherent feature which is uniqueto a group of articles to which the article belongs; a data processorfor decrypting, utilizing one key of an asymmetric key pair, anasymmetrically encrypted identification code for the article comprisingdigital data relating to the inherent features; and a comparator forcomparing the derived data to the decrypted data.